Researchers were hoping to shed light on when, exactly, human ancestors acquired the ability to consume foods containing ethanol, such as fermented fruits. Attempts to answer this question have yielded wildly divergent theories. One theory holds that primates regularly ingested ethanol some 80 million years ago as plants started producing fleshy fruits that could drop and ferment on the ground. Other scientists believe humans started enjoying ethanol just 9,000 years ago when we learned how to ferment foodstuffs.